Indicating lamp circuit for the failure of head lamp circuit



March 28, 1967 H. HARTKORN, .JR

INDICATING LAMP CIRCUIT FOR THE FAILURE OF HEAD LAMP CIRCUIT 4 Sheets-Sheet 1 Filed March 19, 1964 March 28, 1967 HARTKORN. JR 3,311,779

INDICATING LAMP CIRCUIT FOR THE FAILURE OF HEAD LAMP CIRCUIT Filed March .19, 1964 4 Sheets-Sheet 2 air Egg (15 14 Inventor.- fiv/zr/cf flaw/A ar; F

March 28, 1967 H. HARTKORN, JR

INDICATING LAMP CIRCUIT FOR THE FAILURE OF HEAD LAMP CIRCUIT 4 Sheets-Sheet 3 Filed March .19, 1964 March 28, 1967 H. HARTKORN, JR

INDICATING LAMP CIRCUIT FOR THE FAILURE OF HEAD LAMP CIRCUIT 4 Sheets-Sheet 4 Filed March 19. 1964 Fig.5

United States Patent Orifice dfiilljlld Patented Rear. 28, 1W5? l 3 311 779 INDICATED? G LAMP FGR THE FAHJURE 8F LAMP ClliCUlFl Heinrich Hartirorn, J13, Malar=Ernst-Str. It Bad Eurirheim, Germany Filed Mar. 19, 1964, Ser. No. 353,221 Claims priority, application Germany, Mar. 27, 1963, H 43,657; Apr. 29, 1963, H 49,612; Sept. 27, 1963, n 46,224

17 (Claims. (Cl. 315-83) The present invention relates to a circuit arrangement for controlling or monitoring consumer circuits, especially circuits of lights of motor vehicles, without the use of contacts. Particularly in connection with motor vehicles, failure of a headlight not recognized by the driver may lead to serious hazards, but other circuit arrangements also have components which can be monitored to advantage.

Control arrangements are known in which each circuit to be controlled is provided with a relay the armature of which drops open when a failure occurs in said circuit which in turn actuates a contact which closes the circuit of a control or indicating lamp. Inasmuch as the control device is continuously subjected to shocks in motor vehicles, a control circuit operating with such contacts may not properly, or may falsely, indicate the failure of the circuit to be controlled or may not indicate such failure at all.

Other control circuits are known which operate without contacts but in which a control of the circuits is possible only after the respective circuit has been connected to the current source, for instance a battery.

It is, therefore, an object of the present invention to provide a control or monitoring arrangement without contacts for consumer circuits, especially for controlling circuits of lights in motor vehicles, which will overcome the above-mentioned drawbacks.

It is another object of the present invention to provide a control arrangement as set forth in the previous paragraph which is non-sensitive to shocks.

It is a further object of the present invention to provide a control arrangement of the above-mentioned type which makes it possible to control the circuits even when not connected to a current source.

It is still another object of the present invention to provide a control arrangement without contacts which makes it possible to control the consumer circuits independently.

It is a still further object of the present invention to provide a control arrangement as set forth above in which failures in the consumer circuit are indicated in such a way that an interruption of the circuit is readily and immediately noticed.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIGURE 1 shows a first embodiment according to the invention and includes an oscillator, a consumer circuit and a control circuit for the latter;

FIGURE 2 shows a second embodiment according to the invention which differs from that of FIG. 1 in that the control circuit is simplified thereover;

FIGURE 3 shows an arrangement according to the present invention for controlling a plurality of consumer circuits.

FIGURE 4 diagrammatically illustrates a housing combining in an encapsulated unit various elements of the arrangement according to FIGS. 1 to 3 respectively.

FIGURE 5 illustrates a housing for the indicating lamps used in connection with the arrangement according to the present invention.

A circuit arrangement for controlling without contacts consumer circuits, especially circuits of lights of motor vehicles, according to the present invention is characterized primarily in that an oscillator is connected to the feed voltage of the consumer circuits while the oscillating frequency of said oscillator differs from the normal frequency of the consumer circuits. The outlet (Ausgangsgrosse) of said oscillator is connected to the consumer circuit to be controlled and to the control circuit pertaining thereto while the consumer circuit which has a low ohmic resistance at the oscillator frequency is connected to the control circuit which has a high ohmic resistance at said frequency in such a way that it represents a load or shunt for the control circuit.

In a control or circuit arrangement of the above-mentioned type an alternating current is produced which alternating current is simultaneously fed to the consumer circuit and the control circuit therefor. Inasmuch as the consumer circuit has a low ohmic resistance for said alternating current and inasmuch as the consumer circuit is connected to the control circuit of high ohmic resistance in such a way that it represents a load or shunt for said control circuit, an alternating current produced in the oscillator does not flow in the control circuit as long as the consumer circuit is closed. If, however, the consumer circuit is interrupted, for instance due to a failure of a lamp or fuse arranged therein, the load or shunt of the control circuit is removed and an alternating current flows in said control circuit which may be made visible by an indicating lamp, for instance a glow lamp.

Advantageously, the outlet voltage of the oscillator is coupled to the consumer circuit and the control circuit by means of a transducer or transformer (Ubertrager). in this instance the two circuits may be connected to one winding each of the transducer. The consumer circuit, as long as it is closed, then practically represents a shortcircuit for one winding of the transducer so that no voltage is present in that winding of the transducer which is connected to the control circuit. If this short-circuit is removed, for instance by a blowout of the incandescent filament of the lamp to be controlled, the oscillator voltage is fed into the winding connected to the control circuit so that an indicating lamp arranged in said control circuit will light up.

Preferably, the oscillator is transistorized so that it has only a very low current consumption. Advantageously, the oscillator is operated as blocking oscillator Sp errschwinger).

Customarily the consumer circuits of a motor vehicle are rovided with an ignition switch as well as an additional light switch. In order to be able to effect a control also when the lights are turned olf, the light switch is advantageously bridged by an alternating current impedance having a low ohmic resistance at the frequency of the oscillator. As such alternating current impedance, for instance a condenser of high capacity may be employed.

Referring now to the drawings in detail and FIG. 1 thereof in particular, the circuit arrangement shown there in comprises an oscillator circuit generally designated 0, a consumer circuit C and a control circuit K. A transistor 7 of oscillator O is connected to the positive pole ll of a battery through the intervention of an ignition switch 14, a winding 5 of a transducer T, a resistor 8 and one end of a resistor 9 the other end of which is connected to the negative pole 41 of said battery. When said ignition switch 14 is closed, a working voltage is fed to said transistor 7. The emitter 7a of transistor 7 is connected to a tapping 5a of winding 5 while the collector 7b of said transistor is connected to the negative pole 41 of the battery. The oscillator O is furthermore provided with a retroactive or feedback condenser 6 the capacity of which determines the impulse frequency of the oscillator. The arrangement is such that the oscillator operates as blocking oscillator while the frequency thereof is so selected that it differs from that normally encountered in the consumer circuit C.

A consumer 1, for instance a lamp of a motor vehicle, is on one hand connected to the negative pole 41 of the battery and on the other hand to the positive pole of the battery through the intervention of a fuse 2, a secondary winding 3 of transducer T, a light switch 15 and ignition switch 14. The consumer circuit C is bridged by a circuit 4a comprising an electrolytic condenser 4 of high capacity and interposed between switch 15 and the negative pole 41 of the battery. Circuit 4a has a low ohmic resistance and represents a load or shunt for the winding 3 of transducer T of such magnitude that no or only a very low voltage is received at a further winding 19 of transducer T.

Winding 10 of transducer 10 forms a part of the control circuit K which furthermore comprises a glow lamp 13. An alternating voltage produced by oscillator O is received at the winding 1% and rectified by a rectifier 12. Control circuit K is furthermore provided with a resistor 11 and condensers 10a and 1% which serve as bypass or filtering members.

Operation of the arrangement of FIG. 1

When ignition switch 14 is closed, a current flows from the battery through winding 5 of transducer T and the resistors 8 and 9 so that the transistor 7 is supplied with a working voltage. Oscillator O operates as block oscillator while the rhythm of the oscillation produced therein is determined by condenser 6. Transducer or transformer (Ubertrager) T is under the load of the consumer circuit C regardless of Whether switch 15 is opened or closed inasmuch as the consumer circuit C is bridged by the condenser 4. Closing of switch 15 merely brings about that direct current is supplied from the battery to lamp 1 so that the latter will light up in a corresponding position of switch 15.

If lamp 1 burns out, for instance due to a failure of the filament thereof, or if the fuse 2 blows out due to overload, transducer T is no longer under load and an alternating voltage is obtained at winding 19 which alternating voltage is rectified by means of the rectifier 12 and is smoothed by the filters 11, 19 and b. Consequently, glow lamp 133 will light up which indicates that a failure occurred in the corresponding consumer circuit C.

In the arrangement according to FIG. 2, a control or indicator lamp 13a is arranged in the base-collector circuit 7b of the transistor 7. Transistor 7 receives its working voltage from the battery through the intervention of the closed ignition switch 14, the winding 5 of a transducer T and resistors 8 and 9. The arrangement according to FIG. 2 furthermore comprises a retroactive or feedback condenser 13!) which together with the inductance of the winding 5 of transistor T determines the frequency of the oscillator. The control lamp 13a is located in the outlet circuit, i.e. in this instance in the collector circuit of transistor 7. A consumer circuit comprising a lamp 1, a fuse 2 and a winding 3 is arranged in parallel to the series circuit of condenser 13b and lamp 13a. This arrangement serves for damping the feedback or retroactive circuit so that the oscillator cannot start oscillating if the consumer circuit is unbroken. If, however, lamp 1 or fuse 2 fail, no damping occurs any longer and the oscillator starts oscillating. The outlet alternating current thus produced is indicated by control lamp 13a.

FIG. 3 represents a further embodiment of the circuit according to the present invention. A transistor oscillator operates as block oscillator which starts oscillating at a certain rhythm. The frequency of the oscillations is determined by an electrolytic condenser 29 which thus determines the time sequence of the start of the oscillations.

The voltage produced by oscillator 25 is fed to con densers 21, 32, 33, 34 and, if desired, to further condensers, not shown in the drawing, through an outlet transducer 19. Each of these condensers is connected to a further transducer. In the arrangement of FIG. 3 only the circuit of one condenser (condenser 21) is shown in detail. Condenser 21 is connected to one end of a winding 24 of a transducer 18 while the other end of said winding 24 is connected to the outlet transducer 19 of oscillator 25.

A series circuit comprising a lamp 22 to be controlled, a fuse 23 and an electrolyte condenser 26 is connected to a winding 27 of transducer 13. Lamp 22 receives direct current from a battery (not shown) connected to terminals 16 and 17 through the intervention of an ignition switch 3% and a light switch 31. Condenser 26 is arranged between a connecting point 32 of the light switch 31 with the winding 27 and terminal 17 so that an alternating current fed into the system at the winding 27 may fiow regardless of whether switch 31 is open or closed.

A glow lamp 29 is connected to a winding 22 of transducer 18. As long as an alternating current may flow in the circuit connected to the winding 27, glow lamp 29 cannot light up inasmuch as the consumer circuit comprising lamp 22, fuse 23 and condenser 26 has a low ohmic resistance and inasmuch as consequently the transducer 18 is under such load that the voltage drop occurring at condenser 21 is considerably greater than the voltage produced at winding 24. If, however, the circuit is interrupted at the winding 27, for instance due to the fact that the lamp 22 burns out, the load of transistor 18 is eliminated inasmuch as no current can flow any longer in the circuit connected to winding 27. Conse quently, the voltage in winding 24 and also in winding 28 increases and the glow lamp 29 receives a voltage sufficiently high to light up the same in a rhythm pro duced by the block oscillator, i.e. glow lamp 29 lights up at regular intervals.

If the oscillator 25 has a sufficiently high inner resistance, condensers 21., 32, 33, 34, etc. become superflw ous so that the control circuits may be directly connected to the outlet of the oscillator. Block oscillators of high inner resistance may in a manner known per se be obtained by employing surface transistors in an emitter-base configuration and by withdrawing the outlet voltage at the collector.

Advantageously, the elements of the circuit are arranged in a housing and combined to an encapsulated unit by means of cast resin. The housing may be provided with a plug strip to which there may be connected the conductors leading to the circuit. The cast resin serves to protect the circuit against humidity and the soldered joints against shocks while protecting the arrangement against undesired access from the outside. The plug strip makes possible an easy insertion and exchange of the device.

More specifically with regard to FIGS. 4 and 5, the control device shown therein comprises a main body 40 housing the elements of the circuit arrangement according to the present invention and forming an encapsulated unit by means of cast resin. The fuses 2, 23 of the circuit arrangement (see FIGS. 1 to 3 respectively) are arranged in recesses 49a of a lid which is detachably connected to main body 40 by means of a screw 44- while the required number of terminals 46 for connection with the various consumers is provided on top of main body 40.

An additional housing 41 serving as indicating device is detachably connected to main body or housing 40 through the intervention of a multi-polar plug and socket arrangement 42, 43 which is so designed as to exclude an incorrect connection, for instance by making one hole 43a and the corresponding prong of the plug of greater diameter than the other holes and prongs. Indicating device 41 consists of two sections 47, 48 made of different material. Front section 47 is made of plexiglass whereas the rear section 48 is made of a non-transparent synthetic material such as polyvinyl chloride. Section 48 is provided with bores 49 corresponding in number to the number of control lamps. Between sections 47, 48 there is inserted a lettering strip 52.

Front section 47 is provided with conical bores 50 which end shortly before the front surface of front section 47. Inasmuch as these bores operate in the manner of a lens, the light emanated by the control and glowing lamps and flashing on and off is equally distributed over the entire surface. The control lamps are oblong and are located within the bores 49, 5i? and are fixedly held in their respective position by means of cast resin after contacts with the other elements have been effected.

The additional body or indicating device 41 is divided at 51. This affords a possibility easily to distinguish between the left-hand side of the car and the right-hand side of the car. The letters A, F, S, R and B appearing in FIG. 5 on the right-hand side and on the left-hand side of indicating device 41 represent the low beam, high beam, park-light, tail-light and stop-light, respectively. The whole arrangement is of very small size. The main body 4% is preferably arranged at that place in a vehicle where customarily the box containing the fuses is arranged, whereas the indicating device 41 may be incorporated in the panel of the vehicle.

The arrangement according to the invention yields the advantage that failures can be noticed also when the consumer circuits are not connected to a current source. This is particularly advantageous with the control of light circuits of motor vehicles inasmuch as failures can be noticed also during the standstill of the vehicle and at daylight, i.e. when the lights are turned off.

It is, of course, to be understood that the present invention is, by no means, limited to the particular arrangements shown in the drawings but also comprises any modifications within the scope of the appended claims.

I claim:

1. A circuit arrangement for contact free controlling or monitcring of consumer circuits, especially light circuits of motor vehicles, comprising; a transformer having first, second, and third magnetically coupled coil means, a consumer circuit to be controlled or monitored having a resistive load and in series with one of said coil means, a self-excited oscillator having its output side connected to a second one of said coils, a low frequency voltage source for the consumer circuit and connected to said oscillater so as to cause oscillation thereof, an on-oif switch connecting the source to said consumer circuit via said first coil, a control circuit including the third one of said coils and also including indicator means adapted to be energized when said third coil receives energy from said second coil, a component having a high impedance at the frequency of said source and a low impedance at the frequency of said oscillator connected in parallel to said resistive load and said first coil whereby the circuit branch made up of said component and resistive load has a low impedance at the oscillator frequency, said control circuit having a high impedance at the frequency of said oscillator whereby said circuit branch when complete through said resistive load will serve as a shunt for said control circuit and prevent the development of suificient voltage therein to energize said indicator means.

2. A circuit arrangement according to claim 1, in which said indicator means is a glow lamp which becomes illuminated only upon the development of a predetermined voltage in said third coil.

3. A circuit arrangement according to claim 1 in which said oscillator is transistorized.

4. A circuit arrangement according to claim 3, in which said oscillator is a block oscillator.

5. A circuit arrangement according to claim 1, in which said component having low impedance at the oscillator frequency and high impedance at the frequency of said source is a condenser.

6. A circuit arrangement according to claim 1, in which said control circuit is directly connected to the output side of the oscillator, and a circuit component of low impedance in series with said indicating means in said control circuit.

7. A circuit arrangement according to claim 1, in which said voltage source is direct current.

8. A circuit arrangement according to claim 1, in which the consumer circuit is coupled to said oscillator so as to serve as damping resistance for the regenerative circuit of the oscillator when the consumer circuit is continuous and to permit oscillation of the oscillator only when the consumer circuit is interrupted.

9. A circuit arrangement according to claim 1, in which said voltage source is a battery, an ignition switch in the circuit between the battery and said oscillator, the connection from said source to the oscillator being branched ed on the side of the ignition switch opposite the battery and on the side of the on-off switch toward the battery.

18. A circuit arrangement according to claim 1, in which the control circuit includes a rectifier to convert alternating current in the control circuit into direct current.

11. A circuit arrangement according to claim 10, in which the control circuit also includes filtering elements to smooth out pulsations in the current passing through said rectifier.

12. A circuit arrangement according to claim 6, in which the inner resistance of the oscillator is high with regard to the resistance of the consumer circuit.

13. A circuit arrangement according to claim 1, in which elements of the circuits are arranged as a unit, and cast resinous material encapsulating said unit and forming a housing therefor.

14. A circuit arrangement according to claim 13, in which said housing includes a plug or terminal strip to which the conductors of the circuit are connected.

15. An arrangement for monitoring an electric circuit to determine the continuity thereof comprising; a circuit to be monitored, an oscillator, an indicating circuit having an element therein operable to provide an indication when energized, a transformer, a first winding on the transformer connected to the output side of the oscillator to receive current therefrom, a second winding on the transformer connected across the circuit to be monitored whereby a circuit through said second winding will be completed only when the circuit to be monitored is continuous, a third Winding on the transformer connected across said indicating circuit, said circuit to be monitored having a relatively low impedance at the frequency of the oscillator and said indicating circuit having a relatively high impedance at the said frequency, whereby when the circuit to be monitored is continuous insufficient energy is transmitted to the control circuit to energize the said indicating means therein, a source of direct current voltage connected to said oscillator to cause oscillation thereof, and a switch selectively operable to connect said source to said consumer circuit, said source having a frequency substantially lower than that of said oscillator.

16. In combination, in a monitoring arrangement for determining the continuity of an electric circuit; an electric circuit to be monitored, a self-excited oscillator, a control circuit having means therein energizable for providing an indication, a transformer, a first winding on said transformer connected to the output side of said oscillator, a second winding on the transformer connected across the circuit to be monitored, a third winding on the transformer connected across said indicating circuit, said circuit to be monitored having relatively low impedance at the frequency of the oscillator and said indicating circuit having a relatively high impedance at said frequency whereby energization of the said control circuit occurs only under conditions of discontinuity of the circuit to be monitored, a source of voltage of substantially lower frequency than that of the oscillator for energizaticn of said circuit to be monitored, means connecting said source of voltage with said oscillator for supplying energy thereto to cause the oscillator to oscillate, a control switch between the source of voltage and said circuit to be monitored, and means connected with the side of said switch opposite said source of voltage and to the circuit to be monitored at a point remote from said switch and completing the circuit from said second winding through said circuit to be monitored, said means comprising a circuit element having a relatively low impedance at the frequency of said oscillator and a high impedance with respect to said source of voltage.

17. In an automobile having a head lamp circuit, an ignition system and a battery, an ignition switch for connecting the battery with the ignition system, a head lamp switch connecting the battery with the head lamp circuit, an oscillator connected to the ignition switch so as to be energized into a condition of oscillation upon closing of the ignition switch, an indicating circuit having an indicating lamp therein, a transformer having one winding connected across the oscillator output, a second winding connected across said head lamp circuit on the side of said head lamp switch opposite said battery, and a third winding connected across said indicating circuit, and said indicating circuit having a high impedance at the oscillator frequency relative to the impedance of said head lamp circuit whereby under conditions of continuity of said head lamp circuit said indicating lamp is not illuminated, while under conditions of interruption of said head lamp circuit said indicating lamp is illuminated.

References Cited by the Examiner UNITED STATES PATENTS 1,788,597 1/1931 Schultz 315-83 2,719,288 9/1955 Young 340l 2,897,405 7/1959 Briggs et al 315278 X 2,966,614 12/1960 Fayre 315-l X 2,982,881 5/1961 Reich 3l5-205 JAMES W. LAWRENCE, Primary Examiner.

C. R. CAMPBELL, Assistant Examiner. 

17. IN AN AUTOMOBILE HAVING A HEAD LAMP CIRCUIT, AN IGNITION SYSTEM AND A BATTERY, AN IGNITION SWITCH FOR CONNECTING THE BATTERY WITH THE IGNITION SYSTEM, A HEAD LAMP SWITCH CONNECTING THE BATTERY WITH THE HEAD LAMP CIRCUIT, AN OSCILLATOR CONNECTED TO THE IGNITION SWITCH SO AS TO BE ENERGIZED INTO A CONDITION OF OSCILLATION UPON CLOSING OF THE IGNITION SWITCH, AN INDICATING CIRCUIT HAVING AN INDICATING LAMP THEREIN, A TRANSFORMER HAVING ONE WINDING CONNECTED ACROSS THE OSCILLATOR OUTPUT, A SECOND WINDING CONNECTED ACROSS SAID HEAD LAMP CIRCUIT ON THE SIDE OF SAID HEAD LAMP SWITCH OPPOSITE SAID BATTERY, AND A THIRD WINDING CONNECTED ACROSS SAID INDICATING CIRCUIT, AND SAID INDICATING CIRCUIT HAVING A HIGH IMPEDANCE AT THE OSCILLATOR FREQUENCY RELATIVE TO THE IMPEDANCE OF SAID HEAD LAMP CIRCUIT WHEREBY UNDER CONDITIONS OF CONTINUITY OF SAID HEAD LAMP CIRCUIT SAID INDICATING LAMP IS NOT ILLUMINATED, WHILE UNDER CONDITIONS OF INTERRUPTION OF SAID HEAD LAMP CIRCUIT SAID INDICATING LAMP IS ILLUMINATED. 